Tuesday, 14 May 2013

The "prn" , " when necessary" notation and how it may affect the amount of medicine you receive

You see the doctor for severe osteoarthritis pain. You expect the doctor to give you a prescription that can allow you to collect lots of painkillers for standby.

The prescription looks like this

po paracetamol 1 g qds prn 6/12

in humanly language, it means Panadol ( if you are in Singapore) or Tylenol ( brand name for acetaminophen if you are from North America) ,take 1 g  (usually 2 tablets of the 500 mg paracetamol per tablet) four times a day when necessary . Please supply 6 months of the drug...

So if you happen to be in a hospital in Singapore, the way the people at the pharmacy arrives at the number of tablet to give you is like this :

2 tablets x 4 times a day x 30 days per month x 6 months = 1440 tablets of 500 mg paracetamol

Therefore theoretically you are able to collect the full amount of 1440 tablets...But there is the "prn" which means "when necessary"...Only you alone will know how often you need it, the people at the pharmacy will just assume that you do not need such a large quantity of painkillers. They will estimate and give you 20 to 50 tablets, since they assume you will not want to pay for so much painkillers that are not always necessary.

In summary, to save the trouble,when you see the " prn" in your prescription, do tell the people at the pharmacy that you want to collect the full supply so that they will prepare it for you. It will save everyone time